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2005 isuzu ascender
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319 Posts
Discussion Starter #1
I've looked all over but cannot find a table with low/high side pressures for various temperature and humidity ranges. If anyone has one, please post it.

Specifically, I could use 80F or 90F, high humidity (70-90%). I can wait to check until the weather matches if I got these values at least but I'm sure others would benefit from other values in a complete table.

Thanks.
 

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2005 isuzu ascender
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319 Posts
Discussion Starter #2
Anyone have this info or could point to a thread with it?
:undecided
 

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2008 chevy trailblazer_lt
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300 Posts
Not sure what exactly you hope to achieve with this. I don't think there is "exact science" (ie. one to one "things") that you can go by. The proper method for AC service is complete evacuation, and fill with measured amount of r134 not pressures... they are there from "confirmation" of operation. Good luck.

Ambient Temperature
Relative Humidity
Low Side Service Port Pressure
High Side Service Port Pressure
Maximum Left Center Discharge Air Temperature

13-18°C (55-65°F)
0-100%
175-207 kPa (25-30 psi)
1030-1220 kPa (135-175 psi)
7°C (45°F)

19-24°C (66-75°F)
Below 40%
175-254 kPa (25-37 psi)
1200-1430 kPa (160-200 psi)
11°C (52°F)

Above 40%
175-262 kPa (25-38 psi)
1170-1400 kPa (170-210 psi)
11°C (52°F)

25-29°C (76-85°F)
Below 35%
208-288 kPa (30-42 psi)
1370-1570 kPa (150-190 psi)
14°C (57°F)

35-50%
213-292 kPa (31-42 psi)
1350-1570 kPa (160-200 psi)
14°C (57°F)

Above 50%
216-300 kPa (31-44 psi)
1340-1550 kPa (160-200 psi)
15°C (59°F)

30-35°C (86-95°F)
Below 30%
242-328 kPa (35-48 psi)
1510-1750 kPa (200-240 psi)
17°C (63°F)

30-50%
246-335 kPa (36-49 psi)
1500-1740 kPa (200-240 psi)
17°C (63°F)

Above 50%
252-346 kPa (37-50 psi)
1490-1730 kPa (200-240 psi)
19°C (66°F)

36-41°C (96-105°F)
Below 20%
281-366 kPa (41-53 psi)
1680-1920 kPa (240-280 psi)
19°C (66°F)

20-40%
285-374 kPa (41-54 psi)
1670-1920 kPa (245-285 psi)
21°C (70°F)

Above 40%
292-383 kPa (42-56 psi)
1670-1910 kPa (250-265 psi)
22°C (72°F)

42-46°C (106-115°F)
Below 20%
322-400 kPa (47-58 psi)
1850-2070 kPa (250-290 psi)
22°C (72°F)

Above 20%
326-410 kPa (47-60 psi)
1840-2060 kPa (260-300 psi)
23°C (73°F)

47-49°C (116-120°F)
Below 30%
360-426 kPa (52-62 psi)
1990-2150 kPa (290-330 psi)
24°C (75°F)

PS. This is an "excerpt" from a GM service "page".
 

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2005 isuzu ascender
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319 Posts
Discussion Starter #5
Thanks

Thank you budwich. This is exactly what I was looking for.

I agree with you that if there is an A/C problem then it is correct to evacuated, fix it, then refill the system by weight not pressure.

I just want to check the system to be sure it is not excessively overfilled... I fixed an AC issue on my other vehicle a few weeks ago and hooked the gauges up to the Isuzu just to verify the gauges were working properly. I noticed the pressure seemed high, so I just wanted a rough idea of the correct pressures to see if it really is an issue or not. (3-4 years ago the Isuzu AC was serviced and I was concerned they may have overfilled it...

Thanks again for the help.
 
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